The present disclosure relates generally to fluid dispensing systems. More specifically, this disclosure relates to positive displacement pumps for fluid dispensing systems.
Fluid dispensing systems, such as fluid dispensing systems for paint, typically utilize positive displacement pumps to pull the fluid from a container and to drive the fluid downstream. Typically, positive displacement pumps contain a check valve in the pump inlet. During operation, the check valve in the pump inlet opens to allow the fluid into the pump and then closes as the pump pressurizes the fluid in the pump chamber and moves the fluid to the pump outlet. In some cases, a check valve can also be included in the pump outlet to prevent the fluid from flowing back into the positive displacement pump between pump intervals.
After each use of the positive displacement pump, the check valves must be flushed (i.e. rinsed and cleaned by flowing water or another solvent through the check valves) to remove old fluid so that the old fluid does not contaminate new fluid in future uses of the positive displacement pump. Flushing the old fluid out of the check valves is especially important when the positive displacement pump is used in applying paint as the old paint can contaminate the color and texture of the new paint. Internal components and seals inside the check valves can create tight spaces and corners inside the check valve that are difficult to clean when flushing the check valves.